<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
</head>
<body>

</body>
<script>
    var o = {
        name: 'jim',
        age: 19
    };
    o.__proto__ = {
        gender: '男'
    };
    console.log('name' in o);
    console.log('gender' in o);
</script>
</html>